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Date: Mon, 6 Jul 2020 12:20:26 +0000
From: "Liu, Yi L" <yi.l.liu@...el.com>
To: Auger Eric <eric.auger@...hat.com>,
"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
"baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
"joro@...tes.org" <joro@...tes.org>
CC: "Tian, Kevin" <kevin.tian@...el.com>,
"jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
"Raj, Ashok" <ashok.raj@...el.com>,
"Tian, Jun J" <jun.j.tian@...el.com>,
"Sun, Yi Y" <yi.y.sun@...el.com>,
"jean-philippe@...aro.org" <jean-philippe@...aro.org>,
"peterx@...hat.com" <peterx@...hat.com>,
"Wu, Hao" <hao.wu@...el.com>,
"stefanha@...il.com" <stefanha@...il.com>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 02/15] iommu: Report domain nesting info
Hi Eric,
> From: Auger Eric <eric.auger@...hat.com>
> Sent: Monday, July 6, 2020 5:34 PM
>
> On 7/4/20 1:26 PM, Liu Yi L wrote:
> > IOMMUs that support nesting translation needs report the capability info
> need to report
> > to userspace, e.g. the format of first level/stage paging structures.
> >
> > This patch reports nesting info by DOMAIN_ATTR_NESTING. Caller can get
> > nesting info after setting DOMAIN_ATTR_NESTING.
> >
> > Cc: Kevin Tian <kevin.tian@...el.com>
> > CC: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > Cc: Alex Williamson <alex.williamson@...hat.com>
> > Cc: Eric Auger <eric.auger@...hat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
> > Cc: Joerg Roedel <joro@...tes.org>
> > Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > ---
> > v3 -> v4:
> > *) split the SMMU driver changes to be a separate patch
> > *) move the @addr_width and @pasid_bits from vendor specific
> > part to generic part.
> > *) tweak the description for the @features field of struct
> > iommu_nesting_info.
> > *) add description on the @data[] field of struct iommu_nesting_info
> >
> > v2 -> v3:
> > *) remvoe cap/ecap_mask in iommu_nesting_info.
> > *) reuse DOMAIN_ATTR_NESTING to get nesting info.
> > *) return an empty iommu_nesting_info for SMMU drivers per Jean'
> > suggestion.
> > ---
> > include/uapi/linux/iommu.h | 78
> ++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 78 insertions(+)
> >
> > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> > index 1afc661..1bfc032 100644
> > --- a/include/uapi/linux/iommu.h
> > +++ b/include/uapi/linux/iommu.h
> > @@ -332,4 +332,82 @@ struct iommu_gpasid_bind_data {
> > } vendor;
> > };
> >
> > +/*
> > + * struct iommu_nesting_info - Information for nesting-capable IOMMU.
> > + * user space should check it before using
> > + * nesting capability.
> alignment?
oh, yes, will do it.
> > + *
> > + * @size: size of the whole structure
> > + * @format: PASID table entry format, the same definition with
> > + * @format of struct iommu_gpasid_bind_data.
> the same definition as struct iommu_gpasid_bind_data @format?
right. yours is much better.
> > + * @features: supported nesting features.
> > + * @flags: currently reserved for future extension.
> > + * @addr_width: The output addr width of first level/stage translation
> > + * @pasid_bits: Maximum supported PASID bits, 0 represents no PASID
> > + * support.
> > + * @data: vendor specific cap info. data[] structure type can be deduced
> > + * from @format field.
> > + *
> > + *
> +===============+===================================================
> ===+
> > + * | feature | Notes |
> > + *
> +===============+===================================================
> ===+
> > + * | SYSWIDE_PASID | PASIDs are managed in system-wide, instead of per |
> > + * | | device. When a device is assigned to userspace or |
> > + * | | VM, proper uAPI (userspace driver framework uAPI, |
> > + * | | e.g. VFIO) must be used to allocate/free PASIDs for |
> > + * | | the assigned device. |
> > + * +---------------+------------------------------------------------------+
> > + * | BIND_PGTBL | The owner of the first level/stage page table must |
> > + * | | explicitly bind the page table to associated PASID |
> > + * | | (either the one specified in bind request or the |
> > + * | | default PASID of iommu domain), through userspace |
> > + * | | driver framework uAPI (e.g. VFIO_IOMMU_NESTING_OP). |
> > + * +---------------+------------------------------------------------------+
> > + * | CACHE_INVLD | The owner of the first level/stage page table must |
> > + * | | explicitly invalidate the IOMMU cache through uAPI |
> > + * | | provided by userspace driver framework (e.g. VFIO) |
> > + * | | according to vendor-specific requirement when |
> > + * | | changing the page table. |
> > + * +---------------+------------------------------------------------------+
> Do you foresee cases where BIND_PGTBL and CACHE_INVLD shouldn't be
> exposed as features?
sorry, I didn't quite get it. could you explain a little bit more. :-)
> > + *
> > + * @data[] types defined for @format:
> > + *
> +================================+==================================
> ===+
> > + * | @format | @data[] |
> > + *
> +================================+==================================
> ===+
> > + * | IOMMU_PASID_FORMAT_INTEL_VTD | struct iommu_nesting_info_vtd |
> > + * +--------------------------------+-------------------------------------+
> > + *
> > + */
> > +struct iommu_nesting_info {
> > + __u32 size;
> > + __u32 format;
> > + __u32 features;
> > +#define IOMMU_NESTING_FEAT_SYSWIDE_PASID (1 << 0)
> > +#define IOMMU_NESTING_FEAT_BIND_PGTBL (1 << 1)
> > +#define IOMMU_NESTING_FEAT_CACHE_INVLD (1 << 2)
> In other structs the values seem to be defined before the field
not sure. :-) I mimics the below struct from uapi/vfio.h
struct vfio_iommu_type1_dma_map {
__u32 argsz;
__u32 flags;
#define VFIO_DMA_MAP_FLAG_READ (1 << 0) /* readable from device */
#define VFIO_DMA_MAP_FLAG_WRITE (1 << 1) /* writable from device */
__u64 vaddr; /* Process virtual address */
__u64 iova; /* IO virtual address */
__u64 size; /* Size of mapping (bytes) */
};
> > + __u32 flags;
> > + __u16 addr_width;
> > + __u16 pasid_bits;
> > + __u32 padding;
> > + __u8 data[];
> > +};
> > +
> > +/*
> > + * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info
> > + *
> spurious line
yes, will remove this line.
Regards,
Yi Liu
> > + *
> > + * @flags: VT-d specific flags. Currently reserved for future
> > + * extension.
> > + * @cap_reg: Describe basic capabilities as defined in VT-d capability
> > + * register.
> > + * @ecap_reg: Describe the extended capabilities as defined in VT-d
> > + * extended capability register.
> > + */
> > +struct iommu_nesting_info_vtd {
> > + __u32 flags;
> > + __u32 padding;
> > + __u64 cap_reg;
> > + __u64 ecap_reg;
> > +};
> > +
> > #endif /* _UAPI_IOMMU_H */
> >
> Thanks
>
> Eric
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